By conjugating human albumin to agarose, affinity chromatography columns have been developed which are highly effective in removing bilirubin from whole blood. Hemoperfusion for one hour in jaundiced rats has demonstrated removal of virtually the entire circulating bilirubin pool by such columns, with no significant damage to formed blood elements. Studies of the effectiveness of these columns in the management of neonatal jaundice in newborn monkeys are nearing completion. Parallel studies in newborn sheep, which approximate the size of human neonates, are also being peformed. These latter studies are focusing on evaluating various physiologic and biochemical disturbances which may result from hemoperfusion. The recognition during the past year that hemoperfusion through albumin-agarose columns may result in destruction of platelets and white cells in certain species, has led to the development of techniques for avoiding platelet and white cell loss. These techniques have been found to be applicable, in addition, to hemoperfusion through activated charcoal and through charged and neutral synthetic resins.